When running MSBuild static graph restore display additional log messages when project format is not known to MSBuild

src/NuGet.Core/NuGet.Build.Tasks.Console/MSBuildStaticGraphRestore.cs

@@ -104,6 +104,13 @@ public async Task<bool> RestoreAsync(string entryProjectFilePath, IDictionary<st
                 return false;
             }
 
+            if (string.Equals(Path.GetExtension(entryProjectFilePath), ".sln", StringComparison.OrdinalIgnoreCase)
+                    && dependencyGraphSpec.Restore.Count == 0)
+            {
+                MSBuildLogger.LogInformation(string.Format(CultureInfo.CurrentCulture, Strings.Log_NoProjectsForRestore));
+                return true;
+            }
+
             try
             {
                 return await BuildTasksUtility.RestoreAsync(
@@ -534,14 +541,26 @@ private static LibraryIncludeFlags GetLibraryIncludeFlags(string value, LibraryI
         /// <param name="entryProjectPath">The full path to the main project or solution file.</param>
         /// <param name="globalProperties">An <see cref="IDictionary{String,String}" /> representing the global properties for the project.</param>
         /// <returns></returns>
-        private static List<ProjectGraphEntryPoint> GetProjectGraphEntryPoints(string entryProjectPath, IDictionary<string, string> globalProperties)
+        private List<ProjectGraphEntryPoint> GetProjectGraphEntryPoints(string entryProjectPath, IDictionary<string, string> globalProperties)
         {
             // If the project's extension is .sln, parse it as a Visual Studio solution and return the projects it contains
             if (string.Equals(Path.GetExtension(entryProjectPath), ".sln", StringComparison.OrdinalIgnoreCase))
             {
                 var solutionFile = SolutionFile.Parse(entryProjectPath);
 
-                return solutionFile.ProjectsInOrder.Where(i => i.ProjectType == SolutionProjectType.KnownToBeMSBuildFormat).Select(i => new ProjectGraphEntryPoint(i.AbsolutePath, globalProperties)).ToList();
+                IEnumerable<ProjectInSolution> projectsKnownToMSBuild = solutionFile.ProjectsInOrder.Where(i => i.ProjectType == SolutionProjectType.KnownToBeMSBuildFormat);
+                IEnumerable<ProjectInSolution> projectsNotKnownToMSBuild = solutionFile.ProjectsInOrder.Except(projectsKnownToMSBuild);
+
+                if (projectsNotKnownToMSBuild.Any())
+                {
+                    IList<string> projects = projectsNotKnownToMSBuild.Select(project => project.ProjectName).ToList();
+
+                    MSBuildLogger.LogInformation(string.Format(CultureInfo.CurrentCulture,
+                        Strings.Log_ProjectsInSolutionNotKnowntoMSBuild,
+                        projects.Count, string.Join(",", projects)));
+                }
+
+                return projectsKnownToMSBuild.Select(i => new ProjectGraphEntryPoint(i.AbsolutePath, globalProperties)).ToList();
             }
 
             // Return just the main project in a list if its not a solution file

src/NuGet.Core/NuGet.Build.Tasks/PublicAPI.Unshipped.txt

@@ -0,0 +1,2 @@
+static NuGet.Build.Tasks.Strings.Log_NoProjectsForRestore.get -> string
+static NuGet.Build.Tasks.Strings.Log_ProjectsInSolutionNotKnowntoMSBuild.get -> string

src/NuGet.Core/NuGet.Build.Tasks/Strings.resx

@@ -175,4 +175,12 @@
   <data name="Error_MissingRestoreGraphOutputPath" xml:space="preserve">
     <value>Cannot write the dependency graph spec because the `RestoreGraphOutputPath` is missing.</value>
   </data>
+  <data name="Log_ProjectsInSolutionNotKnowntoMSBuild" xml:space="preserve">
+    <value>The solution contains '{0}' project(s) '{1}' that are not known to MSBuild. Ensure that all projects are known to be MSBuild before running restore on the solution.</value>
+    <comment>0 - number of projects not known to msbuild
+1 - list of projects</comment>
+  </data>
+  <data name="Log_NoProjectsForRestore" xml:space="preserve">
+    <value>The solution did not have any projects to restore, ensure that all projects are known to be MSBuild and that the projects exist.</value>
+  </data>
 </root>

test/NuGet.Core.FuncTests/Msbuild.Integration.Test/MsbuildRestoreTaskTests.cs

@@ -704,6 +704,68 @@ await SimpleTestPackageUtility.CreateFolderFeedV3Async(
             }
         }
 
+        [PlatformFact(Platform.Windows)]
+        public Task MsbuildRestore_WithStaticGraphRestore_MessageLoggedAtDefaultVerbosityWhenThereAreNoProjectsToRestore()
+        {
+            using (var pathContext = new SimpleTestPathContext())
+            {
+                // Set up solution, project, and packages
+                var solution = new SimpleTestSolutionContext(pathContext.SolutionRoot);
+
+                var net461 = NuGetFramework.Parse("net461");
+
+                var project = SimpleTestProjectContext.CreateLegacyPackageReference(
+                    "a",
+                    pathContext.SolutionRoot,
+                    net461);
+
+                solution.Projects.Add(project);
+                solution.Create(pathContext.SolutionRoot);
+
+                var result = _msbuildFixture.RunMsBuild(pathContext.WorkingDirectory, $"/t:restore {pathContext.SolutionRoot} /p:RestoreUseStaticGraphEvaluation=true",
+                    ignoreExitCode: true);
+
+                result.Success.Should().BeTrue(because: result.AllOutput);
+                result.AllOutput.Should().Contain("The solution did not have any projects to restore, ensure that all projects are known to " +
+                    "be MSBuild and that the projects exist.", because: result.AllOutput);
+            }
+
+            return Task.CompletedTask;
+        }
+
+        [PlatformFact(Platform.Windows)]
+        public Task MsbuildRestore_WithStaticGraphRestore_MessageLoggedAtDefaultVerbosityWhenAProjectIsNotKnownToMSBuild()
+        {
+            using (var pathContext = new SimpleTestPathContext())
+            {
+                // Set up solution, project, and packages
+                var solution = new SimpleTestSolutionContext(pathContext.SolutionRoot);
+
+                var net461 = NuGetFramework.Parse("net461");
+
+                var project = SimpleTestProjectContext.CreateLegacyPackageReference(
+                    "a",
+                    pathContext.SolutionRoot,
+                    net461);
+
+                solution.Projects.Add(project);
+                solution.Create(pathContext.SolutionRoot);
+
+                string newSlnFileContent = File.ReadAllText(solution.SolutionPath);
+                newSlnFileContent = newSlnFileContent.Replace("FAE04EC0-301F-11D3-BF4B-00C04F79EFBC", Guid.Empty.ToString());
+                File.WriteAllText(solution.SolutionPath, newSlnFileContent);
+
+                var result = _msbuildFixture.RunMsBuild(pathContext.WorkingDirectory, $"/t:restore {pathContext.SolutionRoot} /p:RestoreUseStaticGraphEvaluation=true",
+                    ignoreExitCode: true);
+
+                result.Success.Should().BeTrue(because: result.AllOutput);
+                result.AllOutput.Should().Contain($"The solution contains '{solution.Projects.Count}' project(s) '{project.ProjectName}' that are not known to MSBuild. " +
+                    "Ensure that all projects are known to be MSBuild before running restore on the solution.", because: result.AllOutput);
+            }
+
+            return Task.CompletedTask;
+        }
+
         [PlatformTheory(Platform.Windows)]
         [InlineData(true)]
         [InlineData(false)]